1. Field of the Invention
The invention relates to a method for queue recognition by means wireless vehicle-to-vehicle communication, in which an ego vehicle, in which the method for queue recognition is performed, receives speed and position values from surrounding vehicles situated in the reception area of the vehicle-to-vehicle communication.
The vehicle-to-vehicle communication is part of the vehicle-to-surroundings communication. In this case, a vehicle interchanges information with its surroundings by sending and receiving messages. The messages usually also relate to vehicle-specific values that are recorded by sensors, for example, or obtained in another way, in a single vehicle prior to sending and are then stored. In general, the messages can therefore particularly also contain any type of information or values that characterize the vehicle state. By way of example, they may be speed and position values, but also other values or information that is/are specific to a driving situation, such as the steering, or else values that are not specific to a driving situation and relate to other properties of the vehicle, such as the vehicle type.
2. Related Art
On the basis of the present level of development, vehicle-to-vehicle communication has provision for the determined values and information to be compiled in a standardized method and conditioned in a likewise standardized message. By way of example, the underlying standard is the ITS standard. In this case, ITS is the abbreviation for the term “Intelligent Transportation System”. The effect achieved by this is that the messages can be received universally, that is to say including by other vehicles, for example regardless of the type of manufacturer.
In addition, the ITS standard has provision for these messages to be transmitted either continuously, i.e., at defined intervals of time of greater or lesser length, or on the basis of an event. The continuous messages are also referred to as “Cooperative Awareness Messages”, or CAM messages for short, in the ITS standard. The CAM messages are transmitted omnidirectionally and periodically, that is to say in a similar manner to a beacon, by one vehicle and can be received by any appropriately configured other vehicle in the reception area.
The messages are transmitted using various wireless communication paths. By default, the ITS standard has provision for the messages to be interchanged on a WLAN-based radio channel. However, it is also possible to use other radio channels, particularly for sending the messages. By way of example, WO 2009/074655 A1 discloses a method that involves the use of a further radio channel for sending particularly relevant messages. The additional radio channel is a radio channel that is used for a wireless access and authorization system.
In addition, the vehicle-to-vehicle communication has provision for particular messages to be transmitted on the basis of an event that has occurred. These messages are known as DENM (“Decentralized Environmental Notification Messages”). On the basis of the ITS standard, such messages are transmitted in the case of a suddenly occurring event, such as an accident. Thus, vehicles that are in the surroundings of the vehicle transmitting the DENM messages, i.e., in the reception area around this vehicle, can be warned of this event. By way of example, the DENM messages allow vehicles to be informed about an accident that has taken place in front of them, for example.
However, the transmission of a DENM message frequently requires the occurrence of a sudden, temporally and spatially unforeseeable event. There are traffic situations in which a critical situation arises as a result of continuous alteration of the situation of a vehicle or a group of vehicles, however. Thus, the flow of traffic on a road can change merely as a result of the number of vehicles on this road, for example. Accordingly, critical situations can arise without a preceding sudden event, including without a DENM message being transmitted. Furthermore, the transmission of a DENM message for a queue end presupposes that the vehicle is already in the queue or has already recognized the queue.
In addition, situations may also arise in which the flow of traffic is altered by virtue of road users who are not participating in the vehicle-to-vehicle communication participating in the vehicle scenario and influencing it. These may be pedestrians or other vehicles that are not equipped with an appropriate communication system, for example. Thus, in city traffic or on highways, it is a frequent occurrence that the volume of traffic continually increases and thus slow-moving traffic or a queue arises. These traffic situations are distinguished by a usually significantly reduced average speed of the vehicles. In the case of a queue, the vehicles may come to a complete standstill, in which the speed of the vehicles is zero. In the case of such a continual alteration in the flow of traffic, there is no sudden critical event that would warn the subsequent traffic. In particular, the gradual slowing of the flow of traffic means that a DENM message is not transmitted or at least is transmitted belatedly.
However, it is desirable for the driver of a vehicle to be informed early about such an alteration, precisely because one of the most frequent causes of an accident in road traffic is the occurrence of a queue and in that case particularly the queue end. The queue end is the link between normally moving traffic, moving at the recommended maximum speed on highways, for example, and the queue, i.e., in extreme cases stationary vehicles. Hence, the speed differences in the vehicles are great in the region of the queue end. This results in a significantly increased probability of an accident. This can be exacerbated by geographical circumstances, such as a complicated and confusing road profile, poor visibility conditions, the weather in general or high speeds of the vehicles in normally moving traffic before the end of the queue.
At present, there are already various opportunities for warning the drivers of a vehicle about a queue or queue end. These can be coarsely divided into two systems. In the first system, an attempt is made to distribute the volume of traffic evenly over the roads. They therefore aim at informing the driver as early as possible. The second systems have the aim of actively intervening in the driving scenario. The objective in this case is to avoid an accident or at least to reduce the consequences of an accident.
By way of example, one way of providing early information for the driver involves informing him about an impending queue by alternating signage or information gantries. These may be installed at the edge of the road and may possibly also recommended alternative routes. These warn the driver about the queue so early that he is able to adapt his journey route accordingly. By way of example, he can take the next exit on a highway and use a country road instead. Such traffic control systems monitor the traffic either by sensors in or on the road, or the traffic is observed manually. Therefore, the installation and/or operation are costly and involved. This results in the systems usually being limited to areas of high population density and, even in those areas, monitoring the traffic usually only on a coarse-meshed basis.
Early warning is likewise the aim of conventional traffic announcements on the radio. Although the announcements are available over a wide area, they allow the driver only coarse orientation. In the meantime, data are also being transmitted over radio frequencies, for example the RDS (“Radio Data System”) service, in addition to the traffic announcements. In recent years, the prevalence and availability of such traffic information have been significantly improved. In some cases, the traffic information is thus linked directly to vehicle-internal navigation systems via TMC (“Traffic Message Channel”). This allows a level of spatial and temporal precision to be achieved that enables the driver, independently or using the navigation system, to find an improved route. However, the success is wholly dependent on the quality of the traffic information received. The temporal and spatial precision is frequently insufficient for active intervention in the driving scenario, however.
Driver assistance systems can influence the driving situation of the vehicle. To this end, the surroundings are monitored by vehicle-inherent sensors, for example. The driver assistance systems therefore work autonomously. When the driver assistance system recognizes a critical traffic situation, it either warns the driver visually and/or audibly and recommends that a braking process be initiated, for example. In the meantime, some systems also allow direct intervention in the driving scenario, for example by virtue of the initiation of an automatic braking process. The sensors used, such as radar or lidar, are long range, in principle, but separation effects can arise. This means that although a distant vehicle can be recorded on the open road, it is sometimes not, or not completely, recorded when there is a further object inbetween. Similarly, a vehicle that is behind a summit cannot be recorded. Therefore, the range is at least restricted in road traffic. In dense traffic, the range may thus also be limited to the immediately adjacent vehicle. Such driver assistance systems are expensive and warn the driver only about a sudden hazard. They reach their limits in dense traffic, however.